Remove software and opengl flow implementations

This simplifies the code base A LOT.

YACReader/mouse_handler.cpp

@@ -3,17 +3,11 @@
 #include <QtWidgets>
 
 #include "configuration.h"
+#include "goto_flow_widget.h"
 #include "magnifying_glass.h"
 #include "render.h"
 #include "viewer.h"
 
-#include "goto_flow.h"
-#ifndef NO_OPENGL
-#include "goto_flow_gl.h"
-#else
-#include <QtWidgets>
-#endif
-
 using namespace YACReader;
 
 YACReader::MouseHandler::MouseHandler(Viewer *viewer)